This invention relates to cellular communication systems and, in particular, to a distributed cellular communication system architecture that supports the co-existence of multiple technologies in the various system components for the control and processing of cellular communication connections.
The problem with existing cellular communication networks is that they are technology specific and the introduction of new technologies in a cellular communication network results in major changes in the cellular call processing software to accommodate the new cellular communication network components. The introduction of new technologies in cellular communication networks is therefore impeded by this limitation, since the transition to a new technology in even a single cellular communication network element represents a costly investment in changes necessitated in the remaining segments of the cellular communication network to be compatible with the newly added cellular communication network component.
In addition to technology differences, there are also differences in the standards that are used to implement the signaling protocol and signal interfaces between cellular communication network elements. Within the United States, Common Channel Signaling systems use the ANSI Signaling System No. 7 (SS7) protocol while outside of the United States the International Signaling System No. 7 (ITU-7) protocol is used. Thus, there is an incompatibility in the signaling protocols and interfaces presented by a cellular communication network component if the component is designed to conform to a standard that differs from the standard used to implement the remainder of the cellular communication network.
The above described problems are solved and a technical advance achieved by the present distributed cellular communication system architecture for the co-existence of multiple technologies, which uses the mapping table capability of the Asynchronous Transfer Mode network and the multi-layer nature of the signaling protocol that is used in cellular communication networks to transparently interconnect cellular communication network elements that use different technologies and/or signaling protocols. The Asynchronous Transfer Mode network and the multi-layer signaling protocol are used to interconnect the various signal processing elements that comprises the cellular communication network, including the following elements: Mobile Switching Center (MSC), Selection/Distribution Unit (SDU), a plurality of base stations, a circuit switched communication network, and a packet switched communication network. This collection of elements is used to implement the control and processing of cellular communication connections.
The present distributed cellular communication system architecture avoids the need for significant changes in the cellular call processing software to accommodate new cellular communication network components by inserting signal routing data into the Asynchronous Transfer Mode network routing tables to thereby interconnect signals between compatible endpoints that are connected to the Asynchronous Transfer Mode network. The layer 1 and layer 2 protocols of the Asynchronous Transfer Mode network are used as the conduit that carries the signals between endpoints and are the same for all technologies and signaling protocols. The data contained in the upper layers of the multi-layer protocol are technology and signaling protocol specific, but are not interpreted by the Asynchronous Transfer Mode network, they are simply routed to a designated endpoint pursuant to the data entries in the routing tables of the Asynchronous Transfer Mode network.
Therefore, different technologies and/or different signaling protocol and signal interfaces between cellular communication network elements can be implemented in the cellular communication system without the need to update all of the call processing software components.